Bermudagrass Growth in Hydraulic-Fracturing-Drilling-Fluid-Contaminated Soil.

Bermudagrass Growth in Hydraulic-Fracturing-Drilling-Fluid-Contaminated Soil

D.C. Wolf* and K.R. Brye

Hydraulic fracturing is the process of injecting aqueous solutions at high pressure to break apart rock formations and increase the amount of natural gas released.  The solution is recovered and has been land-applied as one disposal technique. Excessive fluid application can result in increased soil salinity that can inhibit or prevent plant growth.  The objective of this greenhouse study was to evaluate the effects of inorganic fertilizer, broiler litter, and Milorganite^® and soil depth interval (0-15 cm or 0-30 cm) on the growth of bermudagrass [Cynodon dactylon (L.) Pers] in soil that was collected from a site that had been contaminated with fracturing fluid and was initially devoid of vegetation.  Amendment rates were added to provide 62.5 mg of plant available N/kg.  In soil from the 0-15 cm depth, electrical conductivity (EC), Na, and Cl levels were 4.23 dS/m, 2994 mg/kg, and 5603 mg/kg, respectively. For the 0-30 cm depth, EC, Na, and Cl levels were 3.65 dS/m, 2550 mg/kg, and 5020 mg/kg, respectively. Bermudagrass was sprigged and harvested after 9 weeks and shoot, root, and total biomass determined. Addition of inorganic fertilizer, broiler litter, or Milorganite^® resulted in greater shoot biomass compared to unamended soil. Soil depth interval did not affect shoot biomass production, but the plants grown in 0-30-cm-depth soil resulted in greater root biomass, length, volume, and surface area compared to soil from the 0-15 cm depth.  At harvest, soil total inorganic N levels in the amended bermudagrass treatments were approximately 50 mg/kg less than the amended non-vegetative treatments.  Plowing the soil to a depth of 30 cm, applying any of the three amendments, and sprigging bermudagrass could be used as part of an effective management strategy to establish vegetation in soil contaminated with hydraulic fracturing drilling fluid.